Therapeutic current and means for producing the same



Sept 15, 1942- R. J. LINDQUlsT 2,295,585

THERAPEUTIC CURRENT AND MEANS FOR PRODUCING THE SAME vvA l/v v v ATTORNEY.

Sept. y15, 1942- R. J. LlNDQulsT Filed Sept. 16, 1939 2 Sheets-Sheet 2 Tf a SR. wm W ,.v Wm% J r m L R 0 o 1:31@ 2-,@ iw, HF". '1 14N 44g M (um a 4... y 2 .6 n 51,/ ,d I@ 6 v. dan. @30; l W25 i l A TTORN E Y.

Patented Sept. 15, 1942 1 THERAPEUTIC CURRENT AND MEANS FOR PRODUCING THE SAME Robert J. Lindquist, Los Angeles, Calif.

Application September 16, 1939, Serial No. 295,233

(Cl. Z50- 36) Claims.

My invention relates in general to electrotherapy and relates in particular to a new type of therapeutic current and a method and means for producing the same.

It is an object of the present invention to provide a therapeutic current which produces better, quicker, and more lasting results than those currents now employed therapeutically for a similar purpose.

It is an object of the invention to produce a therapeutic current which is patterned after normal nerve currents which are eifective in the natural human body. The present invention has proceeded from the initial consideration that in the normal human body there exists an attunement, from an electrophysical standpoint, of the activating energy or nerve energy and the activated or excited medium consisting of the body (muscalature), etc., which perform their nat-- ural functions when energized by nerve force flowing thereinto through the body nerves. From this line of investigation I have found that the pattern of nerve energy generated in or transmitted through the body nerves are essentially different from those currents which are commonly used in that branch of electrotherapy wherein contractile currents are applied as a therapeutic medium. I have found that these nerve currents are not sine waves nor a close approximation thereof, but consist of short separate and distinct impulses separated by rest intervals which are much longer than the intervalsof nerve stimulus. Each impulse may be shorter than one-thousandth of a second in duration but only 5 to 50 of these impulses are normally supplied per seccond, seldom rising above 100 per second. While one-liftieth or one one-hundredth of a second may appear to be only a very short period, it provides sufficient time for the nerve to prepare for the next impulse or for the energizable medium to prepare for the succeeding stimulus. In keeping with the new understanding of the character of body nerve current my invention provi-des for therapeutic treatment of the human body an externally produced electric current having a wave form of such similarity to the Wave form of body nerve current as to accomplish vastly improved therapeutic results.

It is a further object of the invention to provide a means for producing a therapeutic current comprising electropotential impulses which are spaced apart by periods of rest and it is also an object to provide a therapeutic current and means for producing the same, the current comprising separate impulses spaced apart by periods of time of greater duration than the current impulses.

Itis a further object of the invention to provide means whereby the spacing of separate current impulses may be varied within a desired range, thereby making it possible to tune the frequency of the therapeutic current to the responsive range of the nerves and/or active tissue to which stimulus is to be applied, and also making it possible to readily select a frequency of separate impulses to suit the requirement of a specific treatment to be given.

A further object of the invention is to provide a new therapeutic current and means for producing the same, the therapeutic current comprising spaced impulses patterned after normal human impulses of nerve energy, but having a subordinate compensating wave value'to reduce or minimize the chemical. or galvanic effect which the impulses might otherwise produce in treatment of the body.

It is also an object of the invention to provide an apparatus for producing my therapeutic current having means for varying the frequency of the current impulses.

Further objects of the invention include the provision in the device of separate adjustable means for controlling the active and inactive period and also the modulation of the current delivery, each function being independently controlled.

Further objects and advantages of the invention will be brought out in the following part of the specification.

Referring to the drawings which are for illustractive purposes only:

Fig. 1 is a graph showing comparison of the current impulse of my invention with common form of current impulses used in electrotherapy.

Fig. 2 is a graph to illustrate the range of frequency which may be produced in the practice of my invention.

Fig. 3 is a graph showing different current conditions produced in the practice of the invention.

Fig. 4 is an electrical diagram showing a preferred embodiment of the device for producing the novel therapeutic current.

In the graph, Fig. 1, I show the essential characteristics of my therapeutic wave 5, and also show a common sine wave 6 and a rectied sine wave T, the latter two being common forms of electrical Waves employed in the giving of certain types of treatment for which my Wave is better adapted. Assuming that the ordinates above the abscissa represent positive polarity and the negative ordinates below the abscissa A-A represent negative polarity, the wave 5 comprises, insofar as nerve response is concerned, a sharp or substantially instantaneous impulse 8 comprising a substantially instantaneous rise in potential 9 to a peak Iil, followed by a rapid drop II which curves olf near its lower end to merge with the negative part I2 of the complete alterations forming the wave 5, this subordinate portion of the curve being of comparatively low potential so that its ability to produce a response in nerve or muscle tissue is relatively nil. The current wave 5 is designed to follow the pattern of natural nerve current or potential wave in sufficiently close approximation to satisfactorily stimulate nerves which are treated therewith and to produce a desired response in the musculature.

As shown in Fig. 1, my therapeutic current comprises spaced waves 5, the spacing S of these waves 5 being a multiple of the time T of the current impulse produced by the individual wave 5. In the normal practice of the invention, the impulse time T is made less than two milliseconds (second preferably in the range of the millisecond or less. As graphically shown in Fig. 2, the spacing of the impulses may be varied from Sn to SN, or from 5 to 500 milliseconds. I have provided this range of adjustment for the convenience of the doctor in the selection of treating current for different pathologies. Experience of nearly two years in use of the invention leads strongly towards the conclusion that best or quickest results are obtained where the frequency of the electrical impulses is selected within the range of 5 to 80 per second.

A feature of the present invention is that between each time of impulse there is a period of rest R. as indicated in the graph, Fig. 1. This period of rest is a multiple of the impulse time T, such multiple varying from 4 to approximately 499. In the preferred use of the therapeutic current, that is within the range of normal nerve impulses, the rest period R interposed between the current impulses will vary from 39 to 79 milliseconds, giving the nerve channels ample time to prepare for each succeeding impulse.

Taking into consideration that in the functioning of the body musculature, periods of muscular activity or contraction are ordinarily followed by periods of inactivity or rest, I make it possible to apply the therapeutic current during active periods followed by inactive periods, as shown in the graph I3 of Fig. 3, which graph I3 also indicates that the spacing of the impulses during each active period may be relatively small as at Sn or larger as indicated by SN. The active and inactive periods may be independently varied from a few seconds duration to a duration of 12 to 15 seconds, so that the current may be applied through a very short active period followed by a relatively long inactive or rest period, or vice versa.

As shown in graph I4 of Fig. 3, I provide means for selectively modulating the current intensity so that during an active period it will increase and decrease gradually as indicated at I5 and I6 instead of abruptly increasing and decreasing as indicated at Il and I8 in graph I3 of Fig. 3. The rates of increase and decrease are independently variable as indicated by thc values in, dn, iN, and dN of graph I4.

The preferred form of device by which I produce this therapeutic current is shown in Fig. 4 and includes a timing means by which the active and inactive periods of Fig. 3 are controlled, a modulating means 2| for producing and controlling the increase and decrease of current values, a power generator 22, and a therapeutic current or wave former 23. The members 20 and 2| operate to control the delivery of electrical power from the power generator 22 and the member 23 operates to convert the relatively smooth continuous current from the power generator 22 to the therapeutic current having short impulses interspersed by relatively long periods of rest. In the preferred form of my device an alternating supply circuit, such as the common 110 v. A. C. commercial system, feeds the primary winding 3| of a transformer 32 of the timing means 20. One terminal of the secondary winding 33 of the transformer 32 is connected by a conductor 34 with one terminal of an electromagnet 35, the other terminal of which is connected through a conductor 36 with the plate 37 of a suitable vacuum tube 38 having a grid controlled output, such for example as a triode tube having a grid 39 and a filament 40 fed by a 21/2 Volt secondary transformer winding 4I. The electromagnet 35 when energized attracts a movable switch member 42 and to eliminate vibration of this switch member 42 a condenser 43 is bridged across the energizing circuit between conductors 34 and 35.

When the switch element 42 is attracted by the electromagnet 35 it contacts a contact 44 which is connected through a conductor 45, a variable or adjustable resistance 46 and a fixed resistance 41 with a plate 48 of a full wave rectifying tube 49 having a filament 53 which is connected with one end of the section 5I of the transformer winding 33, the plate 48 being connected through the parts 41, 46, 45, 44, 42, a conductor 52 and a condenser 53 with the opposite end of the section 5I. The second plate 55 of the tube 49 is connected through a conductor 55, a fixed resistance 51, and a variable resistance 58 with a contact 59 forming part of the modulating means 2|. The inner ends of the sections 5I and E0 of the winding 33 of transformer 32 are also connected to a conductor 6I which extends through the modulator means 2| and the power generator 22, and has connection at 62 with the filament 40 of the triode tube 38 and is connected l through a fixed resistance 63 and a variable resistance 64 with a contact 65 positioned so as to be engaged by the movable switch member 42 when the member 42 is released by the electromagnet 35. The modulating means 2| has a movable switch member 65 connected as by a link 61 with the movable switch member 42 so that the member S5 will be pulled into engagement with the Contact 59 when the spring 68 pulls the movable switch member 42 into engagement with the contact 65, there being a contact 69 in the modulating means 2| which is engaged by the movable switch member 56 when the electromagnet 35 pulls the movable switch member 42 into engagement with the contact 44 of the timing device 20. The movable switch member B5 is connected by a conductor 'I0 with the grid 'I2 of triode tubes 'I3 and 14 of the power generator 22, and a condenser 'I5 is bridged across the conductors 6I and 'I0 for the purpose of building up a blocking potential which will be later explained. The contact 69 is connected through a variable resistance 16 and a fixed resistance 11 with the conductor 6| which is connected at 18 in the power generating means 22 with the circuit 19 which supplies the current to the filament 80 of the tubes 13 and 14 to heat the same.

The power generator 22 has a power output circuit comprising conductors 8| and 82 which pass through a filter 83. The conductor 8l is connected at 84 to a central point of the secondary winding 85 of a transformer 86 having a primary winding 81 which is fed from the alternating current supply circuit 30. The conductor 82 is connected to the filaments 80 of the tubes 13 and 14 and the plates 88 of the tubes 13 and 14 are respectively connected through conductors 99 and 90 with the ends of the secondary Winding 85.

The wave forming or converting means 23 has a vacuum tube 9| and associated control element whereby the smooth direct current delivered by the power circuit 8I--82 is transformed or converted into the therapeutic frequency described relative to Figs. 1, 2, and 3. The -tube 9| has a filament 92 energized from a suitable source such as a transformer secondary winding 93, a grid 94 and a plate 95. The filament 92 is connected to the conductor 8| of the power circuit, and the plate 95 is connected to the conductor 82 of the power circuit through a conductor 96 and a portion of the winding 91 of a transformer 98 which is attuned, as by the use of a bridging condenser 99 so as to cooperate in the production of desired voltage graduations in the circuits of the wave forming means 23. The end of the winding 91 opposite to that which is connected through the conductor 96 with the plate 95 is connected through a condenser with the grid 94 and the grid 94 is connected through a variable resistance IOI with the filament 92. When a current potential is delivered from the conductor 8| to the filament 92, current will pass from the plate 95 through a selected portion of the winding 91, namely, that part between the terminals of the conductors 96 and 82 with the result that there will be an abrupt voltage rise in the winding 91, such as represented by the rise 9 of the graph shown in Fig. 1. The entire winding 91 due to the rise of the magnetic flux therein provides a correspondingly high potential which is applied through the condenser to the grid 94 of the tube 9| so that there is a quick blocking potential built up on the grid 94 to interrupt the flow from the conductor 8| through the tube 9| and a portion of the winding 91 to the conductor 82. The foregoing effects happen in such short space of time that the rise 9 appears as a substantially straight line which ends at the peak I0 when the blocking potential is applied to the grid 94 with the result that the potential in the transformer 98 drops off to zero value substantially as represented by the drop I| of Fig. 1. Neutralization or discharge of the potential of the blocking grid 94 occurs relatively slowly owing to the presence of the resistance |05, and by varying the value of the applied resistance IOI, the period of rest between separate impulses 8 may be varied without difficulty through a range even greater than required in the normal operation of my device. Accordingly, it is possible to hold at the grid 94 a blocking potential sufficient to block the flow of electrons from the filament 92 to the plate 95 for a period of time ranging from 2 to 500 milliseconds.

As the blocking potential is gradually drained out through the resistance |0| there will bea gradual drop in the potential effective in the grid 94 and the end of the period of rest R will be reached when the blocking potential of the grid 94 reaches and drops slightly below the potential applied to the filament 92 through the conductor 8| whereupon there will be a flash of electronic energy from the filament 92 to the plate and thence through a portion of the winding 91 to the conductor 82, thereby repeating the cycle of operation. Accordingly, the action in the tube 9| and the parts associated therewith appears to constitute the building up of a blocking potential in the grid 94 which blocking potential is periodically reduced to such point that a flash of power current may pass through from the filament 92 to the plate 95. Accordingly, periodic potential impulses are produced in the Winding 91, the frequency of which may be controlled through manipulation of the variable resistance |0I, substantially without change in the form of the impulse but merely with a change in the spacing of the impulses. An output circuit comprising conductors |02 and |03 is provided, these conductors |02 and |03 connecting the ends of the winding |04 of a potentiometer I 05 through condensers 06 and |01 with spaced points along the transformer winding 91, the amount of the winding 91 included between the conductors |02 and |03 determining the potential produced in the output circuit. The therapeutic current is delivered to the patient through electrodes |08 and |09 connected by 'leads |I0 and III with the potentiometer |05. The condensers |06 and |01 in the output circuit |02- |03 give the therapeutic current compensation so that its effect will be essentially contractile with very little galvanic or chemical effect in the patient. Owing to the presence of these condensers |06 and I 01 each irnpulse 8 is followed by a slight subordinate alternation as indicated by the curve I2 in Fig. 1. This compensates for the galvanic effect of the impulse 8 without provision of suflicient voltage to produce a negative impulse following the ordinate impulse 8.

The elements 20 and 2| serve as a control for the power generator 22 whereby the therapeutic current may be delivered to the patient in active periods spaced by inactive periods. The timing means 2| provides an independent control of the length of the active and inactive periods as follows. When the transformer 32 is initially energized there will be a flow of current from the tube 38 out through the conductor 36 and thence through the electromagnet 35 and the conductor 34 back to the section 60 of the transformer winding 33 so that there will be accordingly an abrupt attraction of the switch member 42 into engagement with the contact 44. The tube 49 will then feed current from the plate 48 through the resistances 41 and 46, the conductor 45, the movable switch member 42, and the conductor 52 to the condenser 53 to build up a potential which is transmitted the grid 39 of the tube to block the flow from the element 40 to the plate 31. The resistances 41 and 46 control the rate at which a blocking potential is built up in the condenser 53 and applied to the grid 39. Depending upon theadjustment of the variable resistance 46 the blocking potential in the grid 39 will be built up relatively fast or slow, and when the current value through the' electromagnet 35 reaches a prescribed low value, for example, about 5 milliameters, the movable switch member 42 will be released and the spring 68 will snap the same over into engagement with the contact 65. This build up cf the blocking potential in the grid 39 may selectively take from one or two to fifteen seconds. When the movable switch member 42 engages the Contact 65 there will be a drainage of the blocking potential from the grid 69 through the resistances B4 and 63 and the conductor 5I which as previously described is connected to the winding 33. The duration of this drainage time is selectively varied by adjusting' the variable resistance 64, and when the blocking potential in the grid 39 is reduced to such extent as to permit a prescribed high cur4l rent value through the circuit 34--36 which includes the electromagnet 35, for example, approximately 18 milliameters, the electromagnet 35 will again act to draw the switch member 42 instantaneously into engagement with the contact 44, thereby starting a new cycle of operation. From the foregoing it will be perceived that the switch member 42 may be snapped back andV forth between the two extreme positions thereof under control exerted by the variable resistances 45 and E4.

Throughout the sequences described in the preceding paragraph a constant potential is applied to the plate 55 of the tube 49, with the result that when the movable switch member of the modulating means 2| is in engagement with the contact 59 there will be a flow of current through the conductor 56, the resistances 51 and 58, the switch member 66, and the conductors 10 to the condenser 'I5 from whence the blocking potential will pass to the grids 12 of the tubes in the power generator 22. Accordingly, there will be a blocking potential built up in the grids l2, the rate of build up of this blocking potential being controlled by the resistances 51 and 58. f

The rate at which the blocking potential is built up in the grids .'2 determines the rate of decrement in the voltage applied to the power output circuit SI-82, and accordingly controls the decrease dit or dN shown in graph I4 of Fig. 3.

If the variable resistance is adjusted to a low resistance value, there will be a rapid build up of blocking potential in the grids 82 which will result in a rapid decrement in the output current of the generator 22 and likewise a relatively sharp 'r1 decrement in the therapeutic current delivered by the wave former 23, as graphically indicated at i3 in Fig. 3. As the effective resistance of the resistor 5B is built up, the time of decrement will be correspondingly increased as graphically indicated at dit and dN. When the movable switch member 42 is moved into engagement with the contact the member BS likewise moves into engagement with the contact E9, thereby ccnnecting the conductor TE) to the conductor 6| through the variable resistance 16, the fixed resistance l?, so that the blocking potential may be then drained from the grids '12. As the blocking potential is drained from the grids 12 the flow of electrons from the filaments 8U to the plates 84 cf the tubes '.'3 and 'I4 will increase and the output cf the power circuit 8l-82 will show a corresponding increase. The time of drainage of the blocking potential from the grids 12 may be varied by adjustment of the resistance 15, the result being that when the drainage resistance is at a low value there will be an abrupt rise in the therapeutic current at the beginning of an active period, as indicated at i1 in Fig. 3, and as the drainage resistance is increased, the rate of increment or the time taken to bring the therapeutic current to maximum value may be varied as graphically indicated at in and iN in graph I4 of Fig. 3. It should be understood, however. that the frequency of the wave 5, the duration of the active and inactive periods and the rate of increment and decrement are independently adjustable functions. That is to say, change in the olf and on periods or change in the increase and decrease in voltage does not change the frequency of the current wave 5, or vice versa.

I claim as my invention:

l. In a system of producing a therapeutic current of the character described, the combination of: a power circuit; and means for controlling active and inactive periods in said power circuit, said means comprising a switch, and means for moving said switch between off and on posii tions comprising an electromagnet connected to said switch so as to actuate the same, a thermionic device having its filament and plate connected in series with said electromagnet, and blocking circuit means connected to the grid of said thermionic device, said blocking circuit means having cooperating controlling elements whereby a blocking potential is periodically applied to said grid to control the flow of current through said electromagnet.

2. In a system for producing a therapeutic current of the character described, the combination of: a power circuit; a power unit to feed said power circuit cdmprising an alternating current transformer and a full wave rectifying means having a control grid means; a control circuit connected to said grid means, said control circuit being connected to a condenser; a current source for feeding current to said control circuit to build up a blocking potential in said condenser and said grid means; and a circuit for draining said blocking potential from said condenser and said grid means, said last named circuit comprising a resistance for controlling the rate of drainage of said blocking potential from said condenser and said grid means.

S. In a system for producing a therapeutic current of the character described, the combination of: a power circuit; a power unit to feed said power circuit comprising an alternating current transformer and a full wave rectifying means having a control grid means; a control circuit connected to said grid means, said control circuit being connected to a condenser; a current source; a variable resistance; means for connecting said current source and said variable resistance in series with said control circuit so as to feed current to said control circuit to build up a blocking potential in said condenser and said grid means; and a circuit for draining said blocking potential from said condenser and said grid means, said last named circuit comprising a variable resistance for controlling the rate of drainage of said blocking potential from said condenser and said grid means.

4. In a system for producing a therapeutic current of the character described, the combination of a power circuit; a power unit to feed said power circuit comprising an alternating current transformer and a rectifying tube means having a control grid means; a control circuit connected to said grid means, said control circuit being connected to a condenser; a current source for feeding current to said control circuit to build up a blocking potential in said condenser and said grid means; and a circuit for source; a variable resistance; means for connecting said current source and said Variable resistance in series with said control circuit so as to feed current to said control circuit to build up a blocking potential in said condenser and said grid means; and a circuit for draining said blocking potential from said condenser and said grid means, said last named circuit comprising a Variable resistance for controlling the rate of drainage of said blocking potential from said condenser and said grid means.

ROBERT J. LINDQUIST. 

